Run Linux command in Perl script as different user

I think this is more a Linux command question, but it resides in a perl script so I'll post in both...

I am running a perl script that automates a linux server account setup and then emails the users (using the mail command) to let them know that the account is ready.  Currently, to send an email I do the following:

             # Open for mail output
             open(MAIL, "|mail -s 'Accout is Ready' -b $blindCopyEmails $userEmail ");
             # add message for mail
             print MAIL $emailMessage;
             # Close/Send mail
             close(MAIL);

When the mail is sent out, it is sent from the root account because the automated perl script is ran by the root account, so the email shows from root@thisdomain.com, but I want it to come from another user account.  If I can run the "mail" command as another user, then it will send the email from that user.  I don't believe the mail command has an arguement for changing the from: field, only the subject, cc, bcc, and sendto.  It is required that the actual perl script is run by the root user.

Any suggestions??  

Thanks,
LTCJ